Since having a few thermostats I decided to test them. Not only if the work,or not. But,comparing them to each other as well. Scratching a line about 1/4" below each of the flanges does make slight differences between them easier to see. A medium size saucepan filled with water,and a length of semi-stiff wire suspends them. An instant read thermometer can be helpful,but not required. Sure enough one of them (both 160 stats.) opened faster,and further than the other. Also noticed Jeg's sells the LT1 thermostat seal separately (#53281),and it's nice to have a couple new ones on hand. My late model C/K pick-up uses the same style stat,and I''l probably repeat this experiment later in the season.